Illumination device

ABSTRACT

An illumination device has a coherent light source, an optical device that diffuses the plurality of coherent light beams and illuminates a predetermined illumination area, and a timing control unit that individually controls incident timing of the plurality of coherent light beams to the optical device or illumination timing of the illumination area, wherein the optical device has a plurality of diffusion regions, the diffusion regions being provided corresponding to the plurality of coherent light beams, the plurality of diffusion regions illuminate the illumination range by diffusion of incident coherent light beams, the plurality of diffusion regions have a plurality of element diffusion regions, the plurality of element diffusion regions illuminate partial regions in the illumination area by diffusion of incident coherent light beams, and at least parts of the partial regions illuminated by the plurality of element diffusion regions are different from one another.

TECHNICAL FIELD

The present invention relates to an illumination device that illuminatesa predetermined illumination area using a coherent light beam.

BACKGROUND ART

Since a laser light source has a longer life than a high pressuremercury lamp or the like, the optical system can be downsized, and thepower consumption is also small, an illumination device and projectiondevice using a laser light source are spreading.

The laser light source has a problem of speckle generation. However,Patent Literature 1 discloses a technique in which a traveling directionof a laser beam is periodically changed to temporally change theincident angle of a laser beam incident on each point of theillumination zone so as to make speckle less noticeable.

CITATION LIST Patent Literature

Patent Literature 1: WO 2012/033174 A

SUMMARY Technical Problem

In order to change the emission color of the illumination zoneilluminated by a laser beam, a plurality of laser beams having differentemission wavelength ranges may be superimposed or a laser beam of aspecific emission wavelength range may be applied to a fluorescentmaterial to perform wavelength conversion.

However, in the conventional illumination device, it is only possible toswitch the emission color only for the entire area illuminated by eachlaser beam. Therefore, in order to change the color spotwise, it is onlynecessary to provide a separate laser light source with a small beamdiameter, and the configuration of the optical system of theillumination device becomes complicated.

The problems to be solved by the present invention are to provide anillumination device which can arbitrarily change the illumination modeof any area in an illumination area without complicating theconfiguration of an optical system.

Solution to Problem

In order to solve the above problem, an aspect of the present inventionprovides an illumination device including: a coherent light source thatemits a plurality of coherent light beams, an optical device thatdiffuses the plurality of coherent light beams and illuminates apredetermined illumination area; and a timing control unit thatindividually controls incident timing of the plurality of coherent lightbeams to the optical device or illumination timing of the illuminationarea; wherein the optical device has a plurality of diffusion regionsthat respective coherent light beam are incident, the diffusion regionsbeing provided corresponding to the plurality of coherent light beams,the plurality of diffusion regions illuminate the illumination range bydiffusion of incident coherent light beams, the plurality of diffusionregions have a plurality of element diffusion regions and the pluralityof element diffusion regions illuminate partial regions in theillumination area by diffusion of incident coherent light beams, and atleast parts of the partial regions illuminated by the plurality ofelement diffusion regions are different from one another.

The plurality of coherent light beams emitted from the coherent lightsource may have different emission wavelength ranges.

The illumination device may include a scanning unit for scanning theplurality of coherent light beams emitted from the coherent light sourceon the optical device.

The scanning unit may include a light scanning device that periodicallychanges a traveling direction of the plurality of coherent light beamsemitted from the coherent light source.

The light scanning device periodically may scan the plurality ofcoherent light beams from the coherent light source on an incidentsurface of the optical device, and the timing control unit mayindividually control the incident timing of the plurality of coherentlight beams to the optical device or the illumination timing of theillumination area in synchronization with a scanning timing of theplurality of coherent light beams by the light scanning device.

The timing control unit may individually control the incident timing ofthe plurality of coherent light beams to the optical device or theillumination timing of the illumination area in synchronization with ascanning timing of the plurality of coherent light beams by the lightscanning device so that an illumination mode of the illumination area isperiodically or temporarily changed.

The timing control unit may individually control the incident timing ofthe plurality of coherent light beams to the optical device or theillumination timing of the illumination area so that an arbitraryselected region in the illumination area and the other region in theillumination area are in different illumination modes.

The timing control unit may individually control the incident timing ofthe plurality of coherent light beams to the optical device or theillumination timing of the illumination area so that an arbitraryselected region in the illumination area is illuminated with a colordifferent from the other region in the illumination area.

The timing control unit may individually control the incident timing ofthe plurality of coherent light beams to the optical device or theillumination timing of the illumination area so that in the illuminationare, only an arbitrary selected region in the illumination area is notilluminated.

The illumination device may include an object detection unit thatdetects an object existing in the illumination area, wherein the timingcontrol unit may individually control an incident timing of theplurality of coherent light beams on the optical device or anillumination timing of the illumination area so that a region of theobject detected by the object detection unit and the other region in theillumination area are illuminated in different illumination modes.

The illumination device may include an object detection unit thatdetects an object existing in the illumination area, wherein the timingcontrol unit may individually control an incident timing of theplurality of coherent light beams on the optical device or anillumination timing of the illumination area so that the illuminationmode of at least one of the object detected by the object detection unitand the peripheral region of the object is different from theillumination mode of the other region in the illumination area.

The timing control unit may individually control a light emission timingof the plurality of coherent light beams emitted by the coherent lightsource.

The optical device may be a hologram recording medium, and the elementdiffusion regions may be element hologram areas that differentinterference fringe patterns are formed.

The optical device may be a lens array group having a plurality of lensarrays, and the element diffusion regions may include the lens arrays.

Advantageous Effects

According to the present invention, it is possible to provide anillumination device that can arbitrarily change an illumination mode ofan arbitrary area in an illumination area without complicating theconfiguration of the optical system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a schematic configuration of an illuminationdevice according to one embodiment of the present invention.

FIG. 2 is a view showing a light scanning device.

FIG. 3 is a view showing how a laser beam diffused by an optical deviceis incident on an illumination zone.

FIG. 4 is a view showing an example in which an illumination color of acentral portion in an illumination zone is different from anillumination color of the other portion of the illumination zone.

FIG. 5 is a view showing an example in which only the central portion inthe illumination zone is made non-illuminated.

FIG. 6 is a view in which three hologram areas are adjacently arrangedalong an incident surface of a hologram recording medium.

FIG. 7 is a view in which three hologram areas are arranged in astacking direction.

FIG. 8 is a view showing a schematic configuration of an illuminationdevice according to a second embodiment of the present invention.

FIGS. 9(a) and (b) are views showing an illumination area illuminated bythe illumination device in FIG. 8.

FIGS. 10(a) and (b) are views each showing an example in which theposition of an image of an object projected onto the illumination zonehas moved.

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will be described below withreference to the drawings. In the drawings attached to the presentspecification, for ease of understanding and ease of understanding, thescales, the dimensional ratios in the length and breadth, and the likeare appropriately changed from those of the actual ones and exaggerated.

In addition, terms, geometric conditions and degrees thereof to be usedin the present specification, for example, terms such as “parallel”,“orthogonal”, “same” and the like, values of length, angle and the likeare strict shall be interpreted including a range that can expectsimilar functions without being bound by meaning.

First Embodiment

FIG. 1 is a view showing a schematic configuration of an illuminationdevice 1 according to the first embodiment of the present invention. Theillumination device 1 in FIG. 1 includes an irradiation device 2 and anoptical device 3. The irradiation device 2 includes the laser lightsource 4, the timing control unit 5, and a scanning unit 6.

The laser light source 4 has the light source unit 7 that emits aplurality of coherent light beams, that is, laser beams. The pluralityof light source units 7 may be provided independently or may be a lightsource module in which the plurality of light source units 7 arearranged side by side on a common substrate. Hereinafter, an example inwhich the emission wavelength ranges of a plurality of coherent lightbeams are different from each other will be mainly described, but theemission wavelength ranges of the plurality of coherent light beams maybe the same. In order to make the emission wavelength ranges of aplurality of coherent light beams different from each other, it issufficient that the laser light source 4 of the present embodiment hasat least two light source units 7 having different emission wavelengthranges, and the number of types of emission wavelength ranges may be twoor more. In order to increase the emission intensity, the plurality oflight source units 7 may be provided for each emission wavelength range.

For example, in the case where the laser light source 4 has a lightsource unit 7 r in a red emission wavelength range, a light source unit7 g in a green emission wavelength range, and a light source unit 7 b ina blue emission wavelength range, by overlapping the three laser beamsemitted from the light source units 7, a white illumination light beamcan be generated.

The timing control unit 5 individually controls the incident timing ofthe plurality of coherent light beams to the optical device 3 or theillumination timing of the illumination area (illumination zone) 10. Ina more specific example, the timing control unit 5 individually controlsthe light emission timing of a plurality of laser light beams havingdifferent light emission wavelength ranges in synchronization with thescanning timing of the plurality of laser light beams by the scanningunit 6. That is, when the plurality of light source units 7 are providedcorresponding to a plurality of laser beams having different emissionwavelength ranges, the timing control unit 5 controls the light emissiontiming at which the laser beams are emitted from the plurality of lightsource units 7 for each light source unit 7. As described above, whenthe laser light source 4 is capable of emitting three laser beams ofred, blue, and green, by controlling the light emission timing of eachlaser beam, it is possible to generate an illumination light beam of acolor in which arbitrary one or more colors of red, blue and green aremixed.

The timing control unit 5 may control the light emission timing from thelaser light source 4, the incident timing of the laser beam incident onthe optical device 3 may be controlled, or the illumination timing atwhich the laser beam diffused by the optical device 3 illuminates theillumination area may be controlled. An example in which the timingcontrol unit 5 controls the light emission timing from the laser lightsource 4 will be mainly described below.

The timing control unit 5 may control whether or not to emit laser beamfrom each light source unit 7, that is, on/off of light emission, andmay switch whether or not to guide the laser beam emitted from eachlight source unit 7 to the incident surface of the scanning unit 6. Inthe latter case, an optical shutter unit (not shown) is provided betweeneach light source unit 7 and the scanning unit 6, and thepassing/blocking of laser beam is switched by the optical shutter unit.

The scanning unit 6 scans a plurality of laser beams emitted by thelight source unit 7 on the optical device 3. The scanning unit 6 maymove the light source unit 7 to cause the respective laser beams to scanon the optical device 3, the optical device 3 may be moved so that eachlaser beam is scanned on the optical device 3, and a light scanningdevice 6 a that changes a traveling direction of the laser beam from thelight source unit 7 may be provided so that each laser beam is scannedon the optical device 3. An example in which the scanning unit 6includes the light scanning device 6 a will be mainly described below.The timing control unit 5 synchronizes the scanning timing of theplurality of laser beams by the light scanning device 6 a so that theillumination mode of the illumination area periodically or temporarilychanges, and controls the light emission timing of each laser beam, theincident timing to the optical device 3, or the illumination timing ofthe illumination area.

The light scanning device 6 a varies the traveling direction of thelaser beam from the laser light source 4 with the lapse of time so thatthe traveling direction of the laser beam does not become constant. As aresult, the laser beam emitted from the light scanning device 6 a isscanned on the incident surface of the optical device 3.

As shown in FIG. 2, for example, the light scanning device 6 a has thereflective device 13 that is rotatable around two rotating axes 11, 12extending in mutually intersecting directions. The laser beam from thelaser light source 4 incident on the reflecting surface 13 a of thereflective device 13 is reflected at an angle corresponding to aninclination angle of the reflecting surface 13 a and travels toward anincident surface 3 a of the optical device 3. By rotating the reflectivedevice 13 around the two rotation axes 11 and 12, the laser beam isscanned on the incident surface 3 a of the optical device 3two-dimensionally. Since the reflective device 13 repeats the operationof rotating around the two rotation axes 11 and 12 at a constant period,for example, the laser beam is repeatedly two-dimensionally scanned onthe incident surface 3 a of the optical device 3 in synchronization withthis period.

In the present embodiment, it is assumed that only one light scanningdevice 6 a is provided, all of the plurality of laser beams emitted fromthe laser light source 4 are incident on the common light scanningdevice 6 a, the traveling direction of the light scanning device 6 a ischanged with the lapse of time, and the optical device 3 is scanned.

The optical device 3 has the incident surface 3 a on which the pluralityof laser beams are incident, and diffuses the plurality of laser beamsincident on the incident surface 3 a to illuminate a predeterminedillumination area. More specifically, the plurality of laser beamsdiffused by the optical device 3 passes through the illumination zone 10and then illuminates an illumination area that is an actual illuminationarea 20.

Here, the illumination zone 10 is an illumination zone of a near fieldilluminated by overlapping each diffusion region 14 in the opticaldevice 3. The illumination area of a far field is often expressed as adiffusion angle distribution in an angular space rather than thedimension of the actual illumination zone. In the present specification,the term “illumination zone” includes a diffusion angle area in theangular space in addition to the actual illumination zone (illuminationarea). Therefore, the illumination area illuminated by the illuminationdevice in FIG. 1 can be a much wider area than the illumination zone 10of the near field shown in FIG. 1

FIG. 3 is a view showing how the laser beam diffused by the opticaldevice 3 is incident on the illumination zone 10. The optical device 3has a plurality of diffusion regions 14 corresponding to the pluralityof laser beams. The corresponding laser beam is incident on eachdiffusion region 14. Each diffusion region 14 diffuses the incidentlaser beam and illuminates the entire region of the illumination zone 10as a whole. Each diffusion region part 14 has the plurality of elementdiffusion regions 15. Each element diffusion region 15 diffuses theincident laser beam and illuminates a partial region in the illuminationzone 10. At least a part of the partial region differs for each elementdiffusion region 15.

The optical device 3 is configured using, for example, the hologramrecording medium 16. The hologram recording medium 16 has, for example,as shown in FIG. 3, a plurality of hologram areas 17. Each of thehologram areas 17 is provided corresponding to each of the plurality oflaser beams having different emission wavelength ranges. Each hologramarea 17 has an incident surface 17 a on which the corresponding laserbeam is incident. Both of the laser beams incident and diffused on theincident surface 17 a of each hologram area 17 illuminate theillumination zone 10. For example, when the hologram recording medium 16has three hologram areas 17, the laser beam diffused in each hologramarea 17 illuminates the entire region of the illumination zone 10.

FIG. 3 shows an example in which three hologram areas 17 are provided inassociation with three laser beams that emit light beams in red, blue,or green; however, the hologram recording medium 16 according to thepresent embodiment may have two or more hologram areas 17 in associationwith two or more laser beams having different emission wavelengthranges. As shown in FIG. 3, when the hologram recording medium 16 hasthree hologram areas 17 corresponding to three laser beams that emitlight beams in red, blue, or green, each hologram area 17 illuminatesthe entire region of the illumination zone 10, so that when the threelaser beams emit light beams, the illumination zone 10 is illuminatedwith a white light beam.

The size, that is, the area of each hologram area 17 in the hologramrecording medium 16 is not necessarily the same. Even if the sizes ofthe respective hologram areas 17 are different, by adjusting theinterference fringe formed on the incident surface 17 a of each hologramarea 17 for each hologram area 17, each hologram area 17 can illuminatethe common illumination zone 10.

Each of the plurality of hologram areas 17 has the plurality of elementhologram areas 18. Each of the plurality of element hologram areas 18illuminates a partial region 19 in the illumination zone 10 by diffusingthe incident laser beam. At least a part of the partial region 19illuminated by each element hologram area 18 is different for eachelement hologram area 18. That is, the partial regions 19 illuminated bythe different element hologram areas 18 are at least partially differentfrom each other.

An interference fringe pattern is formed on an incident surface 17 a ofeach element hologram area 18. Therefore, the laser beam incident on theincident surface 17 a of each element hologram area 18 is diffracted bythe interference fringe pattern on the incident surface 17 a, andilluminates the corresponding partial region 19 on the illumination zone10. By adjusting the interference fringe pattern variously, it ispossible to change the traveling direction of the laser beam diffractedor diffused in each element hologram area 18.

In this manner, the laser beams incident on each point in each elementhologram area 18 illuminate the corresponding partial region 19.Further, the light scanning device 6 a changes incident position andincident angle of the laser beam incident on the respective elementhologram areas 18 with the lapse of time. The laser beam incident intoone element hologram area 18 illuminates the common partial region 19even if the laser beam is incident on any position in the elementhologram area 18. That is, this means that the incident angle of thelaser beam incident on each point of a partial region 19 changes withthe lapse of time. This change in the incident angle is a speed thatcannot be resolved by the human eye, and as a result, the scatteringpattern of the coherent light beam having no correlation is multiplexedand observed in the human eye. Therefore, the speckle generatedcorresponding to each scattering pattern is overlapped and averaged, andis observed by the observer. As a result, in the illumination zone 10,speckle becomes less conspicuous. In addition, since the laser beam fromthe light scanning device 6 a sequentially scans each of the elementhologram areas 18 on the hologram recording medium 16, the laser beamsdiffracted at each point in each element hologram area 18 have differentwave fronts. Therefore, since these laser beams are independentlysuperimposed on the illumination zone 10, a uniform illuminancedistribution in which the speckle is inconspicuous can be obtained inthe illumination zone 10.

FIG. 3 shows an example in which each element hologram area 18illuminates different partial regions 19 in the illumination zone 10.However, a part of the partial region 19 may overlap the adjacentpartial region 19. Further, the size of the partial region 19 may bedifferent for each elementary hologram area 18. Furthermore, it isunnecessary that the corresponding partial region 19 is arranged in theillumination zone 10 according to the arrangement order of the elementhologram area 18. That is, the arrangement order of the element hologramarea 18 in the hologram area 17 and the arrangement order of thecorresponding partial region 19 in the illumination zone 10 are notnecessarily coincident.

The illumination device 1 according to the present embodiment performsillumination control to change illumination color of a part of theillumination area illuminated by the laser beam passing through theillumination zone 10 or not to illuminate only a part of theillumination area as necessary.

FIGS. 4 and 5 show an example in which the illumination mode of thecentral portion 10 a in the illumination zone 10 is different from theillumination mode of the other portion in the illumination zone 10. Inthis case, even also in the illumination area illuminated by the laserbeam passing through the illumination zone 10, the illumination mode ofthe central portion is illuminated differently from the illuminationmode of the portion other than the central portion.

In the example of FIG. 4, the hologram recording medium 16 has threehologram areas 17 corresponding to three laser beams that emit lightbeams in red, green, or blue, in the hologram area 17 for red, theentire region thereof is scanned with the corresponding laser beam, andin the hologram area 17 for green and blue, excluding a part thereof,scanning is performed with the corresponding laser beam. In FIG. 4, ineach of the hologram areas 17, a portion where the corresponding laserbeam is not scanned is shown in white. These hollow portions correspondto the central portion 10 a in the illumination zone 10. Since the redlaser beam scans the entire region of the corresponding hologram area17, the red laser beam illuminates the entire region of the illuminationzone 10. The green and blue laser beams illuminate the portion otherthan the central portion 10 a in the illumination zone 10 in order toscan the portion other than the hollow portion in the correspondinghologram area 17. As a result, the central portion 10 a in theillumination zone 10 is illuminated in red, and the illumination zone 10other than the central portion 10 a is mixed with illumination lightbeams of red, green and blue and illuminated in white.

On the other hand, in FIG. 5, in any of the three hologram areas 17, alaser beam scans a region other than the region corresponding to thecentral portion 10 a in the illumination zone 10. For this reason, thecentral portion 10 a in the illumination zone 10 is a non-illuminationzone that is not illuminated by any color.

In order to individually control the light emission timing of the threelaser beams, by arbitrarily adjusting the light emission timing of thethree laser beams, the timing control unit 5 can illuminate an arbitraryplace in the illumination zone 10 with an arbitrary color. If theillumination mode inside the illumination zone 10 is arbitrarilyadjusted, depending on the illumination mode, it becomes possible toilluminate an arbitrary partial region in the actual illumination areailluminated with the laser beam passing through the illumination zone 10in an arbitrary illumination mode.

As described above, the colors of the three laser beams may be the same.Even if the colors of the three laser beams are the same, according tothe present embodiment, it is possible to arbitrarily change theillumination mode of an arbitrary partial region 10 a in thepredetermined illumination area (illumination zone) 10.

The hologram recording medium 16 can be manufactured by using, forexample, a scattered light beam from a real scattering plate as anobject light beam. More specifically, when the hologram photosensitivematerial which is the base of the hologram recording medium 16 isilluminated with a reference light beam and object light beam made of acoherent light beam having coherency with each other, an interferencefringe due to interference of these light beams is formed on thehologram photosensitive material, and the hologram recording medium 16is manufactured. A laser beam which is a coherent light beam is used asthe reference light beam, and a scattered light beam of an isotropicscattering plate which is available at low cost, for example, is used asthe object light beam.

By illuminating the hologram recording medium 16 with a laser beam fromthe focal position of the reference light beam used for manufacturingthe hologram recording medium 16, a reproduced image of the scatteringplate is generated at the arrangement position of the scattering platewhich is the source of the object light beam used in manufacturing thehologram recording medium 16. When the scattering plate which is thesource of the object light beam used for manufacturing the hologramrecording medium 16 has uniform surface scattering, a reproduced imageof the scattering plate obtained by the hologram recording medium 16 isalso a uniform plane illumination, and a region where the reproducedimage of this scattering plate is generated is the illumination zone 10.

In the present embodiment, illumination control is performed by usingthe optical device 3 so as to change a part of the illumination color inthe illumination area or not to illuminate only a part of theillumination area. In order to perform such illumination control usingthe hologram recording medium 16, the interference fringe pattern formedin each element hologram area 18 becomes complicated. Instead of usingan actual object light beam and reference light beam, such a complicatedinterference fringe pattern can be designed using a computer based onthe scheduled wavelength and incident direction of the reconstructionillumination light beam and the shape and position of the image to bereproduced. The hologram recording medium 30 thus obtained is alsocalled a computer generated hologram (CGH). In addition, a Fouriertransform hologram having the same diffusion angle characteristic ateach point on each element hologram area 18 may be formed by computersynthesis. Furthermore, an optical member such as a lens may be providedon the rear side of the optical axis of the illumination zone 10 to setthe size and position of the actual illumination area.

One advantage of providing the hologram recording medium 16 as theoptical device 3 is that the optical energy density of the laser beamcan be reduced by diffusion, and in addition, another advantage is thatsince the hologram recording medium 16 can be used as a directivitysurface light source, the luminance on the light source surface forachieving the same illuminance distribution can be reduced compared withthe conventional lamp light source (point light source). This cancontribute to improving the safety of the laser beam, and even if thelaser beam having passed through the illumination zone 10 is vieweddirectly with a human eye, there is less possibility of adverselyaffecting the human eye as compared with the case of looking directly ata single point light source.

In the examples shown in FIGS. 1 to 5, the hologram areas 17 for red,green and blue are arranged adjacent to each other along the incidentsurface of each hologram area 17 as shown in FIG. 6. In FIG. 6, thehologram area for red is denoted by 17 r, the hologram area for green isdenoted by 17 g, and the hologram area for blue is denoted by referencenumeral 17 b.

In this way, in addition to arranging the three hologram areas 17adjacent along the incident surface, as shown in FIG. 7, the hologramrecording medium 16 in which the respective hologram areas 17 arearranged in the stacking direction may be used. In this case, theinterference fringe pattern of each hologram area 17 is formed in thelayer of each hologram area 17. In order to ensure that the laser beamreaches, without loss as much as possible, from the surface of thehologram recording medium 16 on which the laser beam from the lightscanning device 6 a is incident to the hologram area 17 on the far side,it is desirable to make the visible light transmittance of each hologramarea 17 as high as possible. Further, when the interference fringepattern is formed at a position overlapping in the stacking direction,the laser beam hardly reaches the layer deeper from the surface.Therefore, as shown in FIG. 5, it is desirable to form the interferencefringe patterns in each layer while being shifted in the stackingdirection.

FIG. 1 shows an example in which the laser beam from the light scanningdevice 6 a diffuses through the optical device 3, but the optical device3 may diffuse and reflect the laser beam. For example, when the hologramrecording medium 16 is used as the optical device 3, the hologramrecording medium 16 may be a reflection type or a transmission type.Generally, the reflection type hologram recording medium 16(hereinafter, reflection type holo) has high wavelength selectivity ascompared with the transmission type hologram recording medium 16(hereinafter, transmission type holo). That is, even when theinterference fringe corresponding to different wavelengths is laminatedthe reflection type holo can diffract a coherent light beam of a desiredwavelength only in a desired layer. Also, the reflection type holo issuperior in that it is easy to remove the influence of a zero orderlight beam. On the other hand, the transmission type holo has a widediffractable spectrum and a wide tolerance of the laser light source 4.However, when the interference fringe pattern corresponding to differentwavelengths is laminated, a coherent light beam of a desired wavelengthis diffracted even in a layer other than the desired layer. Therefore,in general, it is difficult to form a transmission type holo with alaminated structure.

As a specific form of the hologram recording medium 16, a volumehologram recording medium 16 using a photopolymer may be used, avolumetric hologram recording medium 16 of a type that performsrecording using a photosensitive medium containing a silver saltmaterial may be used, and a relief type (emboss type) hologram recordingmedium 16 may be used.

The specific form of the optical device 3 is not limited to the hologramrecording medium 16, and may be various diffusion members that can befinely divided into the plurality of element diffusion regions 15. Forexample, the optical device 3 may be configured using a lens array groupin which each element diffusion region 15 is a single lens array. Inthis case, a lens array is provided for each element diffusion region15, and the shape of each lens array is designed so that each lens arrayilluminates the partial region 19 in the illumination zone 10. At leasta part of the position of each partial region 19 is different. As aresult, similarly to the case where the optical device 3 is configuredusing the hologram recording medium 16, it is possible to change theillumination color of only a part of the illumination zone 10 or toprevent only a part from being illuminated.

FIGS. 4 and 5 shows an example in which a part of the illumination inthe illumination zone 10 is stopped or a part of the illumination coloris changed. However, another method for changing the illumination modeof a part of the illumination zone 10 is conceivable. For example, whenthe laser light source 4 has a plurality of light source units 7 thatemit a light beam in the same emission wavelength range, the lightemission of a part of the light source units 7 may be stopped so thatthe illumination intensity of a part of the inside of the illuminationzone 10 is lower than the illumination intensity of the surroundingarea. Conversely, a part of the illumination intensity in theillumination zone 10 may be higher than the surrounding illuminationintensity. In addition, a part of the inside of the illumination zone 10may be illuminated with flashing. Alternatively, a part of the color inthe illumination zone 10 may be changed continuously or intermittently.

As described above, in the first embodiment, the optical device 3 havingthe plurality of diffusion regions 14 associated with a plurality oflaser beams having different emission wavelength ranges is provided.Each diffusion region 14 has the plurality of element diffusion regions15. Since each of the element diffusion regions 15 illuminates thepartial region 19 in the illumination zone 10, by controlling the timingcontrol unit 5 as to whether or not to irradiate each element diffusionregion 15 with a laser beam, it is possible to make the illuminationmode of an arbitrary area in the illumination zone 10 different from theillumination mode of other region in the illumination zone 10. Forexample, it is possible to change the illumination color of an arbitraryarea in the illumination zone 10 or to prevent only the arbitrarypartial region 19 from being illuminated.

Furthermore, the light scanning device 6 a scans laser beam in eachelement diffusion region 15, and the laser beam incident on each pointin each element diffusion region 15 illuminates the entire region of thepartial region 19. Therefore, the incident angle of the laser beam inthe partial region 19 in the illumination zone 10 changes with the lapseof time, so that a speckle in the illumination zone 10 is lessnoticeable.

Second Embodiment

The second embodiment described below changes the illumination mode ofthe object existing in the illumination zone 10.

FIG. 8 is a view showing a schematic configuration of the illuminationdevice 1 according to the second embodiment of the present invention,FIG. 9 is a view showing the illumination area 20 illuminated by theillumination device 1 in FIG. 8. The illumination device 1 in FIG. 8includes an object detection unit 21 in addition to the configuration ofthe illumination device 1 in FIG. 1. The object detection unit 21detects the object 22 existing in the illumination area illuminated bythe optical device 3. That is, the object detection unit 21 detects theobject 22 existing in the illumination area 20 illuminated by the laserbeam passing through the illumination zone 10 in FIG. 8.

The object detection unit 21 may be a sensor that optically detects theobject 22. For example, an infrared ray is applied from the sensor tothe illumination zone 10, and the presence or absence of the object 22and the position and size of the object 22 may be detected depending onwhether or not the reflected light beam is detected in a predeterminedtime by the sensor. Alternatively, the image of the illumination zone 10may be captured by a camera, and the captured image may be analyzed byimage recognition such as pattern matching to detect the presence orabsence of the object 22 and the position and size of the object 22.

When the object detection unit 21 detects the object 22, the timingcontrol unit 5 controls the light emission timing of the plurality oflight source units 7 according to the position and the size of theobject 22. More specifically, the timing control unit 5 differentiatesthe image of the object 22 projected in the illumination zone 10 and theillumination mode of the peripheral region thereof from the illuminationmode of the other region in the illumination zone 10. In this way, it ispossible to differentiate the illumination mode of the object 22 and theperipheral region of the object 22 from the illumination mode of theother region in the illumination area 20 when the laser beam passingthrough the illumination zone 10 illuminates the actual illuminationarea 20.

For example, as shown in FIG. 9(a), the timing control unit 5 mayperform light emission control not to illuminate the object 22 in theillumination area 20. In this way, when the illumination device 1 inFIG. 9(a) is, for example, a headlight of a vehicle and the object 22 isa human, it is possible to prevent direct exposure of an illuminationlight beam to a human so that a person in the illumination area 20 doesnot feel dazzling by being exposed to head light.

Alternatively, for example, as shown in FIG. 9(b), the timing controlunit 5 may perform light emission control to illuminate the object 22 inthe illumination area 20 with different color. Accordingly, when theillumination device 1 in FIG. 9 is, for example, a headlight of avehicle and the object 22 is a pedestrian, an oncoming vehicle or thelike, it is possible to illuminate the object 22 with a conspicuouscolor such as red and notify the driver of the existence of the object22 to call attention of the driver.

Various methods other than the illumination stop of FIG. 9(a) and theillumination of different colors as shown in FIG. 9(b) are conceivableas the illumination mode of the object 22. For example, when the laserlight source 4 has a plurality of light source units 7 that emit a lightbeam in the same emission wavelength range, the light emission of a partof the light source units 7 may be stopped so that the illuminationintensity of the object 22 is lower than the illumination intensity ofthe surrounding area. Alternatively, the illumination intensity of theobject 22 may be higher than the surrounding illumination intensity.Further, the illumination of the object 22 may be switched to flashingillumination instead of continuous illumination.

As described above, in the second embodiment, the timing control unit 5controls the light emission timing of the plurality of light sourceunits 7 according to the position and size of the object 22 detected bythe object detection unit 21. Therefore, the illumination mode of theobject 22 can be changed from the other region in the illumination area20. This makes it possible to improve the antiglare property of theobject 22 and to inform the existence of the object 22 in an easilyunderstandable manner.

Third Embodiment

The third embodiment tracks the object 22 in the illumination area 20.The configuration of the third embodiment is the same as that of FIG. 8,and the object detection unit 21 detects the object 22 in theillumination area 20.

In order to differentiate the illumination mode of a peripheral region24 of the object 22 in the illumination area 20 from the illuminationmode of other region in the illumination area 20, the timing controlunit 5 controls the light emission timing of each light source unit 7 ofthe laser light source 4. As the illumination mode of the peripheralregion 24 of the object 22, illumination with a color different from theregion other than the peripheral region 24 in the illumination zone 10may be performed, illumination may be stopped only in the peripheralregion 24 in the illumination zone 10, and the flashing illumination maybe performed only on the peripheral region 24 in the illumination zone10.

FIG. 10(a) and FIG. 10(b) are views each showing an example in which theposition of an image of the object 22 projected onto the illuminationzone 10 has moved. In accordance with the position of the image of theobject 22, the region illuminated with different illumination modes alsochanges. In this example, the illumination mode of a total of ninepartial regions 19 around the partial region 19 including the object 22is different from the illumination mode of the other illumination zone10. In FIG. 10(a) and FIG. 10(b), the illumination modes of a total ofnine partial regions 19 including the object 22 are illustrated byshadow lines. However, this shadow line indicates that the illuminationcolor is different from the other region or is a non-illuminationregion.

As shown in FIG. 10 (a) and FIG. 10 (b), if the illumination mode of theperipheral region 24 of the image of the object 22 on the illuminationzone 10 is made different from the illumination mode of the other area,the illumination mode of the surrounding region of the object 22existing on the actual illumination area 20 can be made different fromthe illumination mode of the other region.

The manner of tracking the object 22 is not limited to that shown inFIG. 10. For example, the traveling direction of the object 22 may bedetected and only the movement trajectory of the object 22 may beilluminated on the side opposite to the traveling direction from theposition where the object 22 currently exists. Conversely, the object 22may illuminate in all directions in which the object 22 may proceed inthe future.

As described above, in the third embodiment, the object 22 in theillumination area 20 is continuously detected and the illumination modeof the peripheral region 24 of the object 22 is differentiated from theother region in the illumination area 20. Therefore, even if the object22 is moving, it is possible to track the object 22 by illumination.Thus, for example, the moving object 22 can be continuously photographedat night.

The illumination device according to the first to third embodiments maybe mounted not only in the vehicle but also in a specific place. Inaddition, even when mounted on a vehicle, the vehicle is not limited toa car, but may be various moving bodies such as an aircraft, a train, aship, a diving vehicle and the like.

An aspect of the present invention is not limited to each embodimentdescribed above, but includes various modifications that can beconceived by those skilled in the art, and the effects of the presentinvention are not limited to the contents described above. That is,various additions, modifications and partial deletions are possiblewithout departing from the conceptual idea and gist of the presentinvention derived from the contents defined in the claims and theirequivalents.

REFERENCE SIGNS LIST

1 Illumination device

2 Irradiation device

3 Optical device

4 Laser light source

5 Timing control unit

6 Scanning unit

6 a Light scanning device

7 Light source unit

10 Illumination zone

11, 12 Rotation axis

13 Reflective device

14 Diffusion region

15 Element diffusion region

16 Hologram recording medium

17 Hologram area

18 Element hologram area

19 Partial region

20 Illumination area

21 Object detection unit

22 Object

1. An illumination device comprising: a coherent light source that emitsa plurality of coherent light beams; an optical device that diffuses theplurality of coherent light beams and illuminates a predeterminedillumination area; and a timing control unit that individually controlsincident timing of the plurality of coherent light beams to the opticaldevice or illumination timing of the illumination area, wherein theoptical device has a plurality of diffusion regions that respectivecoherent light beams are incident, the diffusion regions being providedcorresponding to the plurality of coherent light beams, the plurality ofdiffusion regions illuminate the illumination range by diffusion ofincident coherent light beams, the plurality of diffusion regions have aplurality of element diffusion regions, the plurality of elementdiffusion regions illuminate partial regions in the illumination area bydiffusion of incident coherent light beams, and at least parts of thepartial regions illuminated by the plurality of element diffusionregions are different from one another.
 2. The illumination deviceaccording to claim 1, wherein the plurality of coherent light beamsemitted from the coherent light source have different emissionwavelength ranges.
 3. The illumination device according to claim 1,further comprising a scanning unit configured to scan the plurality ofcoherent light beams emitted from the coherent light source on theoptical device.
 4. The illumination device according to claim 3, whereinthe scanning unit comprises a light scanning device that periodicallychanges a traveling direction of the plurality of coherent light beamsemitted from the coherent light source.
 5. The illumination deviceaccording to claim 4, wherein the light scanning device periodicallyscans the plurality of coherent light beams from the coherent lightsource on an incident surface of the optical device, and the timingcontrol unit individually controls the incident timing of the pluralityof coherent light beams to the optical device or the illumination timingof the illumination area in synchronization with a scanning timing ofthe plurality of coherent light beams by the light scanning device. 6.The illumination device according to claim 4, wherein the timing controlunit individually controls the incident timing of the plurality ofcoherent light beams to the optical device or the illumination timing ofthe illumination area in synchronization with a scanning timing of theplurality of coherent light beams by the light scanning device so thatan illumination mode of the illumination area is periodically ortemporarily changed.
 7. The illumination device according to claim 1,wherein the timing control unit individually controls the incidenttiming of the plurality of coherent light beams to the optical device orthe illumination timing of the illumination area so that an arbitraryselected region in the illumination area and the other region in theillumination area are in different illumination modes.
 8. Theillumination device according to claim 7, wherein the timing controlunit individually controls the incident timing of the plurality ofcoherent light beams to the optical device or the illumination timing ofthe illumination area so that an arbitrary selected region in theillumination area is illuminated with a color different from the otherregion in the illumination area.
 9. The illumination device according toclaim 7, wherein the timing control unit individually controls theincident timing of the plurality of coherent light beams to the opticaldevice or the illumination timing of the illumination area so that inthe illumination are, only an arbitrary selected region in theillumination area is not illuminated.
 10. The illumination deviceaccording to claim 1, comprising an object detection unit that detectsan object existing in the illumination area, wherein the timing controlunit individually controls an incident timing of the plurality ofcoherent light beams on the optical device or an illumination timing ofthe illumination area so that a region of the object detected by theobject detection unit and the other region in the illumination area areilluminated in different illumination modes.
 11. The illumination deviceaccording to claim 1, comprising an object detection unit that detectsan object existing in the illumination area, wherein the timing controlunit individually controls an incident timing of the plurality ofcoherent light beams on the optical device or an illumination timing ofthe illumination area so that the illumination mode of at least one ofthe object detected by the object detection unit and the peripheralregion of the object is different from the illumination mode of theother region in the illumination area.
 12. The illumination deviceaccording to claim 1, wherein the timing control unit individuallycontrols a light emission timing of the plurality of coherent lightbeams emitted by the coherent light source.
 13. The illumination deviceaccording to claim 1, wherein the optical device is a hologram recordingmedium, and the element diffusion regions are element hologram areasthat different interference fringe patterns are formed.
 14. Theillumination device according to claim 1, wherein the optical device isa lens array group comprising a plurality of lens arrays, and theplurality of element diffusion regions include the lens arrays.